OBJECTIVES: 1) My principal objective is to determine the basis of deranged albumin homeostasis in rats with either renal failure or experimental nephrosis. I will measure the rate of albumin synthesis in vivo in nephrotic rats to elucidate the influence of dietary protein and of serum oncotic pressure on the rate of albumin synthesis during the establishment of the nephrotic syndrome. 2) I will determine the precise abnormalities in albumin homeostasis in experimental nephrosis and determine what constraints uremia imposes on the synthesis and distribution of albumin. 3) Hepatic intracellular albumin is increased in uremic rats. The additional albumin is found in the cytosol and at least 50% of it is the result of new albumin synthesis. An objective of this is to determine the mechanism whereby newly synthesized albumin appears in the cytosol and whether this represents a pathologic change in the synthetic and/or secretory pathway for albumin. I have demonstrated that dietary tryptophan supplementation greatly ameliorates the proteinuria produced by reduction of renal mass. I plan to determine whether the addition of tryptophan to the diet of rats can reduce proteinuria once it is established.